Volume 7

Vinegar

Background

Vinegar is an alcoholic liquid that has been allowed to sour. It is
primarily used to flavor and preserve foods and as an ingredient in salad
dressings and marinades. Vinegar is also used as a cleaning agent. The
word is from the French
vin
(wine) and
aigre
(sour).

History

The use of vinegar to flavor food is centuries old. It has also been used
as a medicine, a corrosive agent, and as a preservative. In the Middle
Ages, alchemists poured vinegar onto lead in order to create lead acetate.
Called "sugar of lead," it was added to sour cider until it
became clear that ingesting the sweetened cider proved deadly.

By the Renaissance era, vinegar-making was a lucrative business in France.
Flavored with pepper, clovers, roses, fennel, and raspberries, the country
was producing close to 150 scented and flavored vinegars. Production of
vinegar was also burgeoning in Great Britain. It became so profitable that
a 1673 Act of Parliament established a tax on so-called vinegar-beer. In
the early days of the United States, the production of cider vinegar was a
cornerstone of farm and domestic economy, bringing three times the price
of traditional hard cider.

The transformation of wine or fruit juice to vinegar is a chemical process
in which ethyl alcohol undergoes partial oxidation that results in the
formation of acetaldehyde. In the third stage, the acetaldehyde is
converted into acetic acid. The chemical reaction is as follows: CH
3
CH
2
OH=2HCH
3
CHO=CH
3
COOH.

Historically, several processes have been employed to make vinegar. In the
slow, or natural, process, vats of cider are allowed to sit open at room
temperature. During a period of several months, the fruit juices ferment
into alcohol and then oxidize into acetic acid.

The French Orleans process is also called the continuous method. Fruit
juice is periodically added to small batches of vinegar and stored in
wooden barrels. As the fresh juice sours, it is skimmed off the top.

Both the slow and continuous methods require several months to produce
vinegar. In the modern commercial production of vinegar, the generator
method and the submerged fermentation method are employed. These methods
are based on the goal of infusing as much oxygen as possible into the
alcohol product.

Raw Materials

Vinegar is made from a variety of diluted alcohol products, the most
common being wine, beer, and rice. Balsamic vinegar is made from the
Trebbiano and Lambrusco grapes of Italy's Emilia-Romagna region.
Some distilled vinegars are made from wood products such as beech.

Acetobacters are microscopic bacteria that live on oxygen bubbles. Whereas
the fermentation of grapes or hops to make wine or beer occurs in the
absence of oxygen, the process of making vinegars relies on its presence.
In the natural processes, the acetobacters are allowed to grow over time.
In the vinegar factory, this process is induced by feeding acetozym
nutrients into the tanks of alcohol.

Mother of vinegar is the gooey film that appears on the surface of the
alcohol product
as it is converted to vinegar. It is a natural carbohydrate called
cellulose. This film holds the highest concentration of acetobacters. It
is skimmed off the top and added to subsequent batches of alcohol to speed
the formation of vinegar. Acetozym nutrients are manmade mother of vinegar
in a powdered form.

Herbs and fruits are often used to flavor vinegar. Commonly used herbs
include tarragon, garlic, and basil. Popular fruits include raspberries,
cherries, and lemons.

Design

The design step of making vinegar is essentially a recipe. Depending on
the type of vinegar to be bottled at the production plant—wine
vinegar, cider vinegar, or distilled vinegar—food scientists in the
test kitchens and laboratories create recipes for the various vinegars.
Specifications include the amount of mother of vinegar and/or acetozym
nutrients added per gallon of alcohol product. For flavored vinegars,
ingredients such as herbs and fruits are macerated in vinegar for varying
periods to determine the best taste results.

The Manufacturing
Process

The Orleans method

Wooden barrels are laid on their sides. Bungholes are drilled into the
top side and plugged with stoppers. Holes are also drilled into the ends
of the barrels.

The alcohol is poured into the barrel via long-necked funnels inserted
into the bungholes. Mother of vinegar is added at this point. The barrel
is filled to a level just below the holes on the ends. Netting or
screens are placed over the holes to prevent insects from getting into
the barrels.

The filled barrels are allowed to sit for several months. The room
temperature is kept at approximately 85°F (29°C). Samples are
taken periodically by inserting a spigot into the side holes and drawing
liquid off. When the alcohol has converted to vinegar, it is drawn off
through the spigot. About 15% of the liquid is left in the barrel to
blend with the next batch.

The submerged fermentation
method

The submerged fermentation method is commonly used in the production of
wine vinegars. Production plants are filled with large stainless steel
tanks called acetators. The acetators are fitted with centrifugal pumps
in the bottom that pump air bubbles into the tank in much the same way
that an aquarium pump does.

As the pump stirs the alcohol, acetozym nutrients are piped into the
tank. The nutrients spur the growth of acetobacters on the oxygen
bubbles. A heater in the tank keeps the temperature between 80 and
100°F (26-38°C).

Within a matter of hours, the alcohol product has been converted into
vinegar. The vinegar is piped from the acetators to a plate-and-frame
filtering machine. The stainless steel plates press the alcohol through
paper filters to remove any sediment, usually about 3% of the total
product. The sediment is flushed into a drain while the filtered vinegar
moves to the dilution station.

The generator method

Distilled and industrial vinegars are often produced via the generator
method. Tall oak vats are filled with vinegar-moistened beechwood
shavings, charcoal, or grape pulp. The alcohol product is poured into
the top of the vat and slowly drips down through the fillings.

Oxygen is allowed into the vats in two ways. One is through bungholes
that have been punched into the sides of the vats. The second is through
the perforated bottoms of the vats. An air compressor blows air through
the holes.

When the alcohol product reaches the bottom of the vat, usually within
in a span of several days to several weeks, it has converted to vinegar.
It is poured off from the bottom of the vat into storage tanks. The
vinegar produced in this method has a very high acetic acid content,
often as high as 14%, and must be diluted with water to bring its acetic
acid content to a range of
5-6%.

To produce distilled vinegar, the diluted liquid is poured into a boiler
and

The production of vinegar.

brought to its boiling point. A vapor rises from the liquid and is
collected in a condenser. It then cools and becomes liquid again. This
liquid is then bottled as distilled vinegar.

Bascsamic vinegar

The production of balsamic vinegar most closely resembles the production
of fine wine. In order to bear the name balsamic, the vinegar must be
made from the juices of the Trebbiano and Lambrusco grapes. The juice is
blended and boiled over a fire. It is then poured into barrels of oak,
chestnut, cherry, mulberry, and ash.

The juice is allowed to age, ferment, and condense for five years. At
the beginning of each year, the aging liquid is mixed with younger
vinegars and placed in a series of smaller barrels. The finished product
absorbs aroma from the oak and color from the chestnut.

Quality Control

The growing of acetobacters, the bacteria that creates vinegar, requires
vigilance. In the Orleans Method, bungholes must be checked routinely to
ensure that insects have not penetrated the netting. In the generator
method, great care is taken to keep the temperature inside the tanks in
the 80-100°F range (26-38°C). Workers routinely check the
thermostats on the tanks. Because a loss of electricity could kill the
acetobacters within seconds, many vinegar plants have backup systems to
produce electrical power in the event of a blackout.

Byproducts/Waste

Vinegar production results in very little by-products or waste. In fact,
the alcohol product is often the by-product of other processes such as
winemaking and baker's yeast.

Some sediment will result from the submerged fermentation method. This
sediment is biodegradable and can be flushed down a drain for disposal.

The Future

By the end of the twentieth century, grocery stores in the United States
were posting $200 million in vinegar sales. White distilled vinegar
garners the largest percentage of the market, followed in order by cider,
red wine, balsamic, and rice. Balsamic vinegar is the fastest growing
type. In addition to its continued popularity as a condiment, vinegar is
also widely used as a cleaning agent.

Have you tried zucchini frettirs? You use up heaps of zucchini this way.Grate zucchinis. Add herbs/spices/seasoning of your choice. Maybe 1 egg. Maybe a sprinkling of flour. Cut mozzarella or feta into cubes and add. Mix. Shape into paddies and fry in the pan. Don't worry about oozing cheese. (Add salt last and then work quickly, otherwise the mixture gets soggy.)Fritatta with zucchini slices is nice, too.There are also zucchini pickles - very nice. If you are interested I can share the recipe.

This is a very vague description of how vinegar is made but in order to make vinegar you do have to use acetobacter. There are different processes and I have worked with pack generators which use wood chips, acetators which do not require wood chips, but produce vinegar more quickly, and barrels ( balsamic vinegar is produced in this manner)there are different strains of acetobacter.
Where I worked I made a mash containing between 10-12% whole grain alcohol, nutirents ( a sweet yeasty combo), and filtered water. I was making white vinegar. (The initial inoculation mash was about 4% alcohol, nutrients, and filtered water) maintain the temp and air and add your sleepy acetobacter. When the acetobacter get going consuming the alcohol the alcohol content will drop and athe acidity content will increase. DO NOT LET THEM CONSUME ALL THE ALCOHOL! at about .05% discharge about 2/3 of the beginning amount and SLOWLY replace it with the 10-12% mash. The bacs will be consuming while the tank is charging so just do not let the total alcohol content increase more than 5%. (might kill your bacs)(Some bacs can take higher strengths but I am assuming you want to make 115-135 grain vinegar.) Once charge is complete wait, test and repeat. FYI Cider process times are much faster.Hope that was kinda helpful Joevie

Comment about this article, ask questions, or add new information about this topic: